Ok, what do you understand under an agi-built. If you mean something like 3/36 or 6/33 then in my opinion its good that str builds are superior to agi builts. An extreme agi built should be able to run and move extreme fast, but if it had any other advantages it would be horrible.
And want i meant was that a str-built is not superior over an built like 18/24 or 15/24. The advantage of better movement speed (and within mobility in battle, better footwork, better "choose were to fight", etc.) outweighs things like more hp, more damage and higher armour.
I think the point eludes you.
You can have 3 agility, which will work.
12 is better for 4 athletics but still a STR heavy build
1 wpf ( but you can put in what, 120 for free by level 31?)
Agi build - put in 6 WM for a whopping 156 wpf at lvl 31 - underwhelming!
lots of PS, more hitpoints from STR, even use IF.
Hmm.. does PS still seem to affect speed of weapon?
Coupled with overly generous heirloom benefits to armor the str build does get more advantages.
As soon as agi build wears enough armour to offer protection from arrows and horse bumps (and FF) they get slower, effectively nullifying the benefits of agility!
Light armour means some loomed archer can one shot your agility build. Heavy armour STR builds need to be very unlucky while wearing armour to get one shotted by an archer.
Don't make me go on.